Cell surface hydrophobicity of oral Candida dubliniensis isolates following limited exposure to sub‐therapeutic concentrations of chlorhexidine gluconate

Abstract

Candidal adhesion has been implicated as the initial step in the pathogenesis of oral candidiasis and cell surface hydrophobicity (CSH) has been implicated in adhesion to mucosal surfaces. Candida dubliniensis is an opportunistic pathogen associated with recurrent oral candidiasis. Chlorhexidine gluconate is by far the commonest antiseptic mouth wash prescribed in dentistry. At dosage intervals the intraoral concentration of this antiseptic fluctuates considerably and reaches sub-therapeutic levels due to the dynamics of the oral cavity. Hence, the organisms undergo only a limited exposure to the antiseptic during treatment. The impact of this antiseptic following such exposure on CSH of C. dubliniensis isolates has not been investigated. Hence, the main objective of this study was to investigate the effect of brief exposure to sub-therapeutic concentrations of chlorhexidine gluconate on the CSH of C. dubliniensis isolates. Twelve oral isolates of C. dubliniensis were briefly exposed to three sub-therapeutic concentrations of 0.005%, 0.0025% and 0.00125% chlorhexidine gluconate for 30 min. Following subsequent removal of the drug, the CSH of the isolates was determined by a biphasic aqueous-hydrocarbon assay. Compared with the controls, exposure to 0.005% and 0.0025% chlorhexidine gluconate suppressed the relative CSH of the total sample tested by 44.49% (P < 0.001) and 21.82% (P < 0.018), respectively, with all isolates being significantly affected. Although exposure to 0.00125% of chlorhexidine gluconate did not elicit a significant suppression on the total sample tested (7.01%; P > 0.05), four isolates of the group were significantly affected. These findings imply that exposure to sub-therapeutic concentrations of chlorhexidine gluconate may suppress CSH of C. dublinienis isolates, thereby reducing its pathogenicity and highlights further the pharmacodynamics of chlorhexidine gluconate.

Post‐antifungal effect and adhesion to buccal epithelial cells of oral Candida dubliniensis isolates subsequent to limited exposure to amphotericin B, ketoconazole and fluconazole

“…Viable counts of the control and the test were performed after drug removal. As the procedure of drug removal effectively eliminated any carry‐over effect there was virtually no difference on the viable counts of the control and the tests following exposure to already diluted sub‐therapeutic concentrations of the drug as observed in preceding studies . In addition, under Gram‐stain, Gram‐positive yeast cells were seen when Candida were observed under light microscopy before brief exposure to these antifungals and did not reveal any observable changes soon after removal of these drugs (i.e.…”

“…Though there have been preceding studies on antimycotic induced PAFE's and its impact on numerous pathogenic attributes of Candida , mainly on C . albicans, the methodological differences between researchers, in addition to disparities in the concentrations of the drugs used, number and the types of Candida species betrothed, exposure time of the drug and the pathogenic attributes tested make comparisons arduous between the current study with previously studies. Nonetheless, to our knowledge the current study is the first to document the suppression of adhesion to BEC and the PAFE induced by antifungal agents that have a wide spectrum of pharmacodynamic properties (i.e.…”

“…A previously described procedure was used for this purpose . Briefly, yeast cells maintained on Sabouraud's dextrose agar (SDA), were inoculated onto fresh plates and incubated overnight at 37°C for 24 h prior to use.…”

“…Afterwards the supernatant was completely decanted and the pellets were re‐suspended in 6 mL of sterile PBS. This procedure has been used heretofore for drug removal and has shown to minimize the concentration of the drug as much as 10 000 fold, thereby preventing any carry‐over effect of the drug following its removal . Viable counts of the control and the test were performed after drug removal.…”

Impact of short‐term exposure of antifungal agents on hemolysin activity of oral Candida dubliniensis isolates from Kuwait and Sri Lanka

“…Afterwards the supernatant was decanted and the pellets suspended in 3 mL of sterile PBS to be used in the hemolysin assay. This procedure has been used previously for drug removal and has shown to lessen the concentration of the drug 10,000 fold, thereby reducing any carry‐over effect of the drug following its removal . Formation of CFUs of the controls and the tests were performed after drug removal.…”